Apparatus for screening and comminuting



May 5, 1959 A. WORMSEYR 1 APPARATUS-FOR SCREENING AND COMMINUTINQ FiledJan. 7. 1957 APPARATUS FOR SCREENING AND COMMINUTING Arthur Wormser,Tucson, Ariz., assignor to Infilco Incorporated, Tucson, Ariz., acorporation of Delaware Application January 7, 1957, Serial No. 632,694

12 Claims. (Cl. 210-154) This invention relates to an apparatus forintercepting solids in a flowing stream of liquid, such as sewage orother waste liquids, and comminuting the solids. More specifically, theinvention relates to improvements in the combination of a screen andcomminutor described in my. co-pending application, Serial No. 360,039,now Patent No. 2,781,915 of which this application is acontinuation-in-part.

In the said co-pending application a comminutor is mounted in the lowerportion of a channel through which the sewage or other liquid arrives.The comminutor comprises a pair of rollers mounted horizontally acrosssaid channel with their longitudinal axes parallel to one another andprovided with projections on their circumferences arranged so that, uponrotation of the rollers, the projections on one roller pass those on theother with small clearance. The rollers are rotated in the samedirection but at different speeds. A bar screen extends across thechannel from an elevation above the maximum liquid level in the channeldownwardly to an elevation adjacent the comminutor and has a rearwardlyextending end portion. The screen is cyclically cleaned by areciprocating rake. About the downstream side of the rollers and alongthe top of the faster roller plates are provided which serve the doublefunction of preventing not fully comminuted material from reaching thedownstream portion of the channel and of holding the material enteringthe space between the rollers and the plates against the rollers, sothat the material is moved by the rotation of the rollers upwardlyaround the rollers and into the bite. These plates are made of resilientmaterial or are hingedly supported and spring pressed to- Ward therollers, so that they are capable of limited movement away from therollers to permit passage of larger than normal pieces of material. Theend portion of the plate adjacent the top of the fast roller is providedwith prongs which are interlaced with the rearwardly extending endportion of the bar screen, thus closing the gap between the lower end ofthe screen and the comminutor.

With this construction, a part of the lowermost end of the bar screen ofsaid co-pending application cannot be cleaned by the rake due to thepresence of the interlacing prongs. In operation of the apparatus ofsaid copending application I have found that particles tend toaccumulate between the lower ends of the screen bars. The occasionallimited movement of the interlacing prongs between the screen bars,which is caused by larger pieces of material passing between the rollersand the pronged plate and pressing the pronged plate away from theroller, does not suflice to prevent or remove such accumulations ofparticles, and eventually they could build up to a degree to interferewith the proper movements of the rake and of the plate.

I also found in actual operation that material taken around by the fastroller to the bite sometimes was carried off by the slow roller beforeit had been taken' into the bite, whereby comminution was slowed down.

States atent O 2,885,079 Patented May 5, 1959 ice The purpose of theinvention is to correct these conditions and to increase both the speedof comminution and the reliability of operation of the comminutor. Theinvention relates primarily to improvements in the means for cleaningthe lower end of the bar screen. Means are also provided to moreeffectively take material which has been carried close to the bite bythe fast roller, into the bite.

It is an object of this invention to improve the corn minutor-bar screencombination of my said co-pending application.

Another object is to provide means for cyclically cleaning the lower endof the bar screen of said co-pending application.

Another object is to provide the comminutor of my said co-pendingapplication with improved means for holding material to be comminutedagainst the rollers of the comminutor until they are taken into thebite.

Another object is to provide means for preventing entry of oversizedobjects into the space between the rollers and the plates of thecomminutor of said co-pending application.

Other objects will become apparent upon consideration of the detaileddescription and the claims which follow.

To permit cleaning of the lowermost part of the screen I provide meansfor effecting a cyclic movement of the pronged plate away from the fastroller during the end portion of each cycle of reciprocation of therake, whereby the prongs are swung out of the path of travel of the arake as it approaches the lower end portion of the screen,

thus permitting the rake to clean the lowermost portion of the barscreen during each of its cycles of reciprocation. This end portion isfurther cleaned by the motion of the prongs which swipe the lower endportion of the screen in a direction perpendicular to that of the rakeand alternately with the rake. I also shape the rake members so thatthey clean a 'wide area of the rearwardly extending end portion of thescreen.

A cyclic movement of the pronged plate would not be permissible with theelastic construction of all feeder plates of said co-pendingapplication. In the embodiment of said application the three plates moveonly away from the rollers in case an oversized object passes betweenthe rollers and the plates; most of the time the plates are stationary.Therefore, if a cyclic movement of the pronged plate were effected,then, each time the pronged plate would be swung away from the fastroller at the end of a cycle of reciprocation of the rake, a wide gapwould be left between the rearwardly swinging pronged plate and the thenstationary adjacent plate. It is clear that only a small gap whose sizeremains the same under all conditions can be tolerated between theplates, as otherwise incompletely comminuted material might reach thedownstream portion of the channel. Obviously, the size of a gap betweentwo members moving independently of each other will vary.

To overcome this difficulty and simplify the over-all plateconstruction, I use, instead of two of the elastic plates of the priorconstruction, one rigid plate and support it rigidly, leaving only thepronged plate hinged and spring pressed; and I form the pronged plate sothat the gap between the adjacent ends of the two plates remain uniformfor all positions of the pronged plate.

Using one plate of rigid material which is rigidly supported requires afurther change in the construction of the comminutor of said copendingapplication. Since the rigid plate would not permit passage of oversizeobjects, their entry in the space between the plate and the rollers mustbe prevented. To this end I provide what maybe termed an entry battle tothis space which affords an opening between itself and the slow rollerof substantially 3 the same cross sectional area as that of the spacebetween the rigid plate and the rollers.

I also provide means counteracting the tendency of the slow roller tocarry off material taken close to the bite by the fast roller before ithas been taken into the bite.

The invention will be more readily understood by reference to thedrawings, wherein:

Figure l is a side elevation of a screen and comminutor according to theinvention, with part of the framing removed and the comminutor drivemeans omitted;

Figure 2 is a view of the interlacing end portions of the screen andpronged plate in the position shown in full lines in Figure 1 and seenin the direction of the arrow A of Figure l; and

Figure 3 is a cross sectional view along line 33 of Figure 1.

Referring to Figure 1, a bar screen and comminutor assembly is installedin a channel 11 through which sewage or other waste liquid flows in thedirection indicated by arrow 12. The comminutor 15 is mounted in thelower portion of the channel 11, so that at times of lowest flow it willbe at least partially submerged. The screen 16 extends from an elevationabove the maximum liquid level in the channel 11 downwardly to adjacentthe comminutor 15. The assembly may be enclosed in a framework 17 andcan be installed in the channel 11 as a unit.

The comminutor 15 comprises a pair of rollers 20 and 21, which extendacross the channel 11 and have their longitudinal axes arranged parallelto one another. The rollers 20 and 21 have spaced projections or teeth22 on their circumferences. The axes of the rollers are so spaced fromone another and the teeth arranged in such planes of rotation that nopoint of the profile of one of the rollers interferes with any point ofthe profile of the other roller and that, upon rotation of the rollers,the projections of one roller enter the spaces between the projectionsof the other roller but pass the projections with small clearance.

The rollers are driven by any suitable means, not shown, in the samedirection, for example, counterclockwise, as indicated by the arrows inFigure 1, but at different speeds. The relative speeds between the fastroller 20 and the slow roller 21 may be of the order of 5 to l. Afriction clutch may be interposed in the drive of the fast roller and anoverload device may be provided, as is well known in the art.

As shown in Figure l, the screen 16 is curved and has a rearwardlyextending lower end portion 16a. The upper and lower ends of the screen16 are supported from the frame 17.

Material intercepted by the screen 16 is moved along the screen towardthe comminutor 15 by a reciprocating rake 25. The rake 25 has rakemembers 26 corresponding in number to the openings between the barsofthe screen 16 and extending into said openings from the downstreamside of the screen, with their tips on its upstream side. The rakemembers 26 are keyed to, and supported by a shaft 27. The shaft 27 ishingedly supported at its ends by arms 28 which in turn are keyed to ashaft 30. A cyclic reciprocating motion is imparted to the shaft 30 byany suitable means, such as a shaft to which it is connected by means ofan arm 36, connecting rod 37 and crank 38. The shaft 35 is continuouslydriven counterclockwise by any suitable means, not shown.

Each arm 28 has a rearward projection 40 and the two outermost rakemembers 26 have each a projection 41. Each projection 41 is hinged to aspring rod 42 which is urged upwardly by a spring 43. The lower end ofeach spring 43 abuts the projection 40 of the respective arm 28, and theupper-end abuts nuts 44 which hold the spring under the proper tension.Upward movement of each ,ofthe springs 43 is limited by adjustablelocknuts 45 which in normal position touch the respective projection 40.

Due to this construction the arms 28 and rake members 26 normally movetogether on their upward and downward trip. A motion of the rake members26 relative to the arms 28, due to the hinging of shaft 27, can be onlyin clockwise direction. Such a motion of the rake members relative tothe arms 28 happens when motion of the crank 38 tends to move the rake25 downwardly while the rake members 26 are prevented from following bymeeting an obstacle which may be pinched in the screen 16. Hinging ofthe shaft 27 permits the rake members to swing rearwardly to within orbehind the bar screen 16 to pass the obstacle.

The structure so far described is that of said co-pending applicationand is not claimed herein except in as far as it cooperates with theimproved means for cleaning the lower portion of the bar screen 16 andfor carrying material to and taking it into the bite of the rollers20-21.

As in the embodiment of said co-pending application, a plurality offeeder plates is mounted on the downstream side of the rollers 20 and21. One of these plates extends upwardly about the fast roller 20 andhas an upper pronged end interlaced with the lower end of the bars ofthe screen 16. However, while in said co-pending application threefeeder plates were used and all were either made of springy material, orwere hingedly supported and spring pressed against the rollers, in theimproved embodiment of this invention I use only two plates, and 51, andmake one of these, 50, of rigid material and afiix it to a rigid support52. The support 52 may be in the form of a plurality of individualposts, or it may be a single plate, supported from the bottom of theframe 17. If posts are used, they may be covered by a thin plate 53 ofsheet metal or the like to guide the stream of water coming down overthe downstream side of the plate 51 and prevent formation of a whirlwhich might deposit comminuted material under the stationary plate 50.

The pronged plate 51 is also made of rigid material but is hingedlysupported at 55 and spring pressed toward the fast roller, as will bedescribed below. The prongs 56 of the plate 51 enter a small distancebetween the bars of the end 16a of the screen 16, as best shown inFigure 2. To keep this distance uniform when plate 51 swings around itspivot 55, the rearwardly extending end portion 16a of the screen 16 isshaped to form an arc of a circle about pivot 55.

I provide means, which will be described below, whereby the plate 51 ismoved cyclically away from the fast roller 20 once during each cycle ofreciprocation of the rake 25 and at the time when the rake approachesthe lower end of the screen 16. To prevent that during the cyclicmovement of plate 51 a gap opens between the lower end of plate 51 andthe upper end of stationary plate 50, through which not fully comminutedmaterial could pass to the downstream side of the channel 11, the

'lower end of the plate 51 is formed as an arc of a circle around itspivot 55. Due to this construction the small gap between the plates 50and 51 will remain the same for all positions of the plate 51. The rakemembers 26 vare shaped so that they wipe a wide area of the rearwardlyextending portion 16a of the screen, and the stroke of the rake 25 isadjusted so that the rake members extend in their lowermost positionsbeyond the screen, as clearly shown in Figure 1.

In order to obtain a cyclic movement of the plate 51 away from theroller 20 during the end of the downward travel of the rake 25, theplate 51 is connected with the shaft 30 to which the arms 28 of the rake25 are keyed, in the following manner: An arm 60 is fastened to theplate 51. and at its outer end pivotally connected with the lower end ofa rod 61. A second rod 62 is pivotally connected to the upper end of rod61. The lower part of the rod 62 is threaded. The rod 62 is guided in aguide 63 which is supported from the frame 17. The upper portion of therod 62 is encircled by a spring 65 which abuts with its lower endagainst the guide 63 and is held under proper compression by lock nuts66 threaded on the upper end of the rod 62. Links 70 (only one of whichis visible in Figure l) are pivoted to the rod 62 with one end and withthe other end to an arm 71 at 72. The arm 71 in turn is keyed to andmoves with the shaft 30. The free end of the arm 71 is shaped to form anose 73, and a cross member 74 between the links 70, is located at adistance from pivot 72 to register with nose 73. When rake 25 is in anup position, the nose 73 is above and spaced from member 74, and theplate 51 is spring pressed against the fast roller 20.

While the rake 25 travels downwardly, the plate 51 remains springpressed against the fast roller 20 until the rake approaches thelowermost portion of the screen 16, at which time the nose 73 engagesthe cross member 74. This compresses spring 65, whereby feeder plate 51is moved outwardly from the roller 20 and the prongs 56 of the plate 51are swung rearwardly from their normal positions shown in dotted linesin Figure 1 to the positions shown in full lines therein. In their endposition the prongs 56 extend somewhat beyond the rearwardly extendingend portion 16a of the screen 16. With the prongs 56 thus out of theway, the rake 25 can complete its downward travel and due to its shapeclean the entire vertical portion and the front part of the rearwardlyextending portion of the screen, while the entire rearwardly extendingportion 16a is swiped by the movement of the prongs.

To permit adjustment of the outward motion of the plate 51, the pivotpoint of links 70 on rod 62 is made adjustable. For this purpose thelinks are pivotally connected to an internally threaded collar 75 whichis movable along the lower threaded portion of the rod 62 and is held inposition by stop nuts 76 and 77. When the plate 51 is spring pressedtoward the roller 20, the clearance between the plate 51 and the roller20 is preferably the same as between plate 50 and roller 21, to providea passageway between the rollers and plates of substantially uniformcross sectional area. The clearance between plate 51 and roller 20 isadjustable by setting lock nuts 78 at a suitable point along the rod 62.The lock nuts 78 will hit the guide 63 upon expansion of the spring 65and thus limit the expansion in accordance with their position.

Since plate 50 is rigid and cannot move away from the rollers to permitpassage of material which is larger than the normal distance between theplate and the rollers, I bafile the inlet to the space between theroller 21 and the plate 50 to prevent such material from enteringthe'space. The dam-shaped baflle 80, which may be aflixed to the plate50 as by welding, or may be integral therewith, restricts the inletopening 81 to the passageway 82 formed between the plate 50 and theroller 21 substantially to the cross sectional area of said passageway.

As shown in Figure 3, the teeth 22 of the rollers 20 and 21 arerectangular in cross section. The portion of the feeder plate 51 abovethe fast roller 20 is provided on its inside with ribs 85 which extendinto the spaces between the teeth 22 of the roller 20. The ribs 85 serveto press material carried around by the fast roller 20 into the spacesbetween its teeth so that it sticks firmly to the teeth. Since the ribs85 co-act with the teeth 22 of roller 20 at a'location where the teethapproach the bite, the material is safely carried into the bite withoutinterference by the slow roller 21. It will be seen that thescreen-comminutor combination of my said co-pending application has beenimproved in important respects, to afford a more reliable operation ofthe entire device.

I claim:

1. In an apparatus for intercepting solids in a flowing stream of liquidand comminuting them, comprising the combination of a stationary screenhaving a rearwardly extending lower end portion, a reciprocable rakeadapted to move solids intercepted by said screen along said screen,means for cyclically reciprocating said rake, comminuting meanspositioned in said stream to receive said solids from said rake, andwall means mounted adjacent the downstream side of said comminutingmeans and having a pronged end portion interlaced with said rearwardlyextending end portion of said screen, said wall means preventing escapeof not fully comminuted material to downstream of said screen andcomminuting means, the combination with said wall means of means forcyclically moving said pronged end portion to the rear end of saidrearwardly extending end portion of said screen and out of the path oftravel of said rake at a time when said rake approaches said end portionof said SCI'fiBIl.

2. In an apparatus for intercepting solids in a flowing stream of liquidand comminuting them, said apparatus including a stationary bar screen,a reciprocable rake adapted to move solids intercepted by said screenalong said screen, means for cyclically reciprocating said rake, andcomminuting means positioned in said stream adjacent one end position ofsaid rake, the combination with said comminuting means of a pair offeeder plates adjacent the downstream side of said comminuting means,one of said plates being rigidly supported and the other plate beingpivotally supported and spring pressed toward said comminuting means,said pivotally supported plate having a pronged upper end interlacedwith the lower end portion of said screen, means restricting theentrance to the space between said comminuting means and said plates tosubstantially the cross sectional area of said space, and meanseffective to cyclically move said pivotally supported plate against thespring pressure away from said comminuting means and swing its prongedupper end out of the path of said rake at a time when said rake, duringa cycle of reciprocation, approaches said one end position, said lowerend portion of said screen being shaped so that said pronged upper endremains interlaced therewith in all of its positions.

3. In an apparatus for intercepting solids in a flowing stream of liquidand comminuting them, said apparatus including a stationary bar screen,a reciprocable rake adapted to move solids intercepted by said screenalong said screen, means for cyclically reciprocating said rake, andcomminuting means positioned in said stream adjacent one end position ofsaid rake, the combination with said comminuting means of a pair offeeder plates adjacent the downstream side of said comminuting means,one of said plates being rigidly supported and the other plate beingpivotally supported and spring pressed toward said comminuting means,said pivotally supported plate having a pronged upper end interlacedwith the lower end portion of said screen, and means effective tocyclically move said pivotally supported plate against the springpressure away from said comminuting means and swing its pronged upperend out of the path of said rake at a time when said rake approachessaid one end position, the lower end portion of said screen being shapedso that said pronged end of said plate remains interlaced therewith inall of its positions.

4. In an apparatus for intercepting solids in a flowing stream of liquidand comminuting them, said apparatus including a stationary barscreen, areciprocable rake adapted to move solids intercepted by said screenalong said screen, means for cyclically reciprocating said rake, andcomminuting means positioned in said stream adjacent one end position ofsaid rake, the combination with said comminuting means of a pair offeeder plates adjacent the downstream side of said comminuting means,one of said plates being rigidly supported and the other plate beingpivotally supported and spring pressed toward said comminuting means,said pivotally supported plate having a pronged upper end interlacedwith the lower end portion of said screen and a lower end shaped as anare about its pivot point, said lower end portion of said screen beingshaped as an are about said pivot point, and means effective tocyclically move said pivotally supported plate against the springpressure away from said comminuting means and out of the path of saidrake during each cycle of reciprocation of said rate at the time whensaid rake approaches said one end position.

5. In an apparatus for intercepting solids in a stream of liquid flowingthrough a channel and comminuting them, said apparatus including astationary bar screen, a reciprocable rake adapted to move solidsintercepted by said screen along said screen, means for cyclicallyreciprocating said rake, and comminuting means positioned in said streamadjacent on end position of said rake, the combination with saidcomminuting means of a pair of feeder plates adjacent the downstreamside of said comminuting means, a rigid support for one of said plates,said rigid support including a solid plate extending across saidchannel, a pivot support for the other of said plates, and spring meansurging said other plate toward said comminuting means, said pivotallysupported plate having a lower end shaped as an are about said pivotsupport and a pronged upper end interlaced with the lower end portion ofsaid screen, and means effective to cyclically move said pivotallysupported plate against the spring pressure away from said comminutingmeans and swing its pronged upper end out of the path of said rake atthe time when said rake, during a cycle of reciprocation, approachessaid one end position, said lower end portion of said screen beingshaped so that said pronged upper end remains interlaced therewith inall its positions.

6. In an apparatus for intercepting solids in a flowing stream of liquidand comminuting them, comprising the combination of a stationary barscreen, a reciprocable rake adapted to move solids intercepted by saidbar screen along said screen, means for cyclically reciprocating saidrake, and comminuting means positioned in said stream to receive saidsolids from said rake, said comminuting means including a pair ofrollers having longitudinal axes parallel to one another across saidstream, teeth on the surface of said rollers, said rollers being sospaced and said teeth so arranged that at the bite the teeth of oneroller enter the spaces between the teeth of the other roller and passsaid teeth with small clearance, means for driving said rollers in thesame direction and at different speeds, and wall means on the downstreamside of said rollers and having a portion extending along the top of thefaster driven roller, said wall means holding the material entering thespace between said rollers and said wall means against said rollers, thecombination with said wall means of a plurality of ribs extending fromthe side of said wall means facing said rollers and arranged so as toregister with the spaces between teeth of the faster driven rollerapproaching the bite.

7. An apparatus for intercepting solids in a stream of liquid flowingthrough a channel and comminuting them, said apparatus including astraining wall interposed in said channel and having a rearwardlyextending end portion, traveling means adapted to cyclically travelalong said straining wall and move solids intercepted by said strainingwall along said wall, drive means for said traveling means, comminutingmeans positioned to receive said solids from said traveling means, andwall means extending about the downstream side of said comminuting meansand having a pronged end portion interlaced with said rearwardlyextending end portion of said straining wall, said wall means preventingescape of not fully comminuted material to the portion of said channeldownstream of said comminuting means, characterized in that said wallmeans comprise a rigid plate rigily supported a predetermined distancefrom said comminuting means, and a rigid plate hingedly supported andspring pressed toward said comminuting means, said hingedly supportedplate having said pronged end portion interlacing with saidrearwardly'extending end portion of said straining wall, said hingedlysupported plate when pressed toward said comminuting means havingsubstantially the same distance from said comminuting means as saidrigidly supported plate to provide a passageway of substantially uniformcross sectional area between said plates and said comminuting means, adam-shaped member forming inlet means to said passageway restricted tothe cross sectional area of said passageway, and means for cyclicallymoving during the end portion of each cycle of travel of said travelingmeans said hingedly supported plate away from said comminuting means toswing said pronged portion across said rearwardly extending end portionof said straining wall and out of the path of travel of said travelingmeans.

8. An apparatus for intercepting solids in a stream of liquid flowingthrough a channel and comminuting them, said apparatus including astraining wall interposed in said channel and having a rearwardlyextending end portion, traveling means adapted to cyclically travelalong said straining wall and move solids intercepted by said strainingwall along said wall, drive means for said traveling means, comminutingmeans positioned to receive said solids from said traveling means, andwall means extending about the downstream side of said comminuting meansand having a pronged end portion interlaced with said rearwardlyextending end portion of said straining wall, said wall means preventingescape of not fully comminuted material to the downstream portion ofsaid channel, characterized in that said wall means comprise a rigidplate rigidly supported a predetermined distance from said comminutingmeans, and a rigid plate hingedly supported and spring pressed towardsaid comminuting means, said hingedly supported plate having saidpronged end portion interlacing with said rearwardly estending endportion of said straining wall, a damshaped member restricting the inletto the space between said rigidly supported plate and said comminutingmeans, and means for cyclically moving said pronged portion of saidhingedly supported plate to the rear end of said rearwardly extendingend portion of said straining wall and out of the path of travel of saidtraveling means during the end portion of each cycle of travel of saidtraveling means.

9. In an apparatus for intercepting solids in a flowing stream of liquidand comminuting them in said stream, said apparatus including a screenmounted transversely of said stream and partway its depth, said screenhaving a rearwardly extending lower end portion, comminuting meansextending across an unscreened portion of said stream adjacent saidlower end portion of said screen, said comminuting means including apair of parallel spaced rollers having spaced teeth on theircircumferences, means for driving said rollers in the same direction andat different speeds, a rake reciprocable along said screen to movesolids intercepted by said screen toward said comminuting means, andmeans for cyclically reciprocating said rake, the combination with saidrollers of a pair of feeder plates adjacent but spaced from thedownstream side of said rollers, one of said plates being rigidlysupported and the other plate being hingedly supported and springpressed toward the faster driven roller, said hingedly supported platehaving a pronged end interlaced with said rearwardly extending endportion of said screen, balfle means restricting the inlet to the spacebetween said plates and said rollers, ribs extending from the side ofsaid hingedly supported plate facing said faster roller and arranged toregister with the spaces between its teeth, and means cyclically movingsaid hingedly supported plate away from said faster roller to swing saidpronged end to the rear end of said rearwardly extending end portion ofthe screen and out of the path of reciprocation of said rake when saidrake approaches said end portion of said screen, whereby the front partof said rearwardly extending end portion is cleaned by said rake and theentire rearwardly extending end portion is cyclically cleaned by saidprongs moving in a direction perpendicular to the motion of the rake andalternately therewith.

10. In an apparatus for intercepting solids in a flowing stream ofliquid and comminuting them, said apparatus including a screen mountedtransversely of said stream and partway its depth, comminuting meansextending across an unscreened portion of said stream adjacent an endportion of said screen, a rake reciprocable along said screen to movesolids intercepted by said screen toward said comminuting means, saidcomminuting means having spaced teeth circumferentially arranged, meansfor cyclically reciprocating said rake, the combination with saidcomminuting means of a pair of feeder plates adjacent but spaced fromthe downstream side of said comminuting means, one of said plates beingrigidly supported and the other plate being hingedly supportedand-spring pressed toward said comminuting means, said hingedlysupported plate having a pronged end interlaced with said end portion ofthe screen, baflle means restricting the inlet to the space between theplates and said comminuting means to substantially the cross sectionalarea of said space, ribs extending from the side of said hingedlysupported plate facing said comminuting means and arranged to registerwith the spaces between said teeth, and means cyclically moving saidhingedly supported plate away from said comminuting means to swing saidpronged end out of the path of travel of said rake when said rakeapproaches said end portion of said screen, said lower end portion ofsaid screen being shaped so that said pronged end and said lower endportion remain interlaced when said pronged end is swung out of the pathof travel of said rake.

11. In an apparatus for intercepting solids in a flowing stream ofliquid and comminuting them, comprising the combination of a stationaryscreen having a rearwardly extending lower end portion, a reciprocablerake adapted to move solids intercepted by said screen along saidscreen, means including a driven shaft and drive means for said shaftfor cyclically reciprocating said rake, comminuting means positioned insaid stream to receive said solids from said rake, and wall meanspreventing escape of not fully comminuted material to downstream of saidscreen and comminuting means, said wall means being mounted adjacent thedownstream side of said comminuting means and including a hingedlysupported plate having a pronged end portion interlaced with saidrearwardly extending end portion of said screen, the combination withsaid wall means of means for cyclically moving said pronged end portionto the rear end of said rearwardly extending end portion of said screenand out of the path of travel of said rake once during each cycle ofreciprocation of said rake at a time when said rake approaches said endportion of said screen, said means for cyclically moving said prongedend portion comprising a rod hingedly connected to said hingedlysupported plate and to said driven shaft, a spring biasing said rod andnormally urging said hingedly supported plate toward said comminutingmeans, and means for efiecting compression of said spring when said rakemeans approachv said end portion of said screen.

12. In an apparatus for intercepting solids in a flowing stream ofliquid and comminuting them, said apparatus including a stationary barscreen, a reciprocable rake adapted to move solids intercepted by saidscreen along said screen, means for cyclically reciprocating said rakealong said screen, and comminuting means positioned in said streamadjacent the lower end position of said rake, the combination with saidcomminuting means and said screen of a pair of feeder plates on thedownstream side of said comminuting means, one of said plates beingrigidly supported and the other being pivotally supported and springpressed toward said comminuting means, said pivotally supported plateclosing the gap between the lower end portion of said screen and saidcomminuting means and having an upper end portion extending into thelower end portion of the path of reciprocation of said rake, meansefiective to cyclically move said pivotally supported plate against saidspring pressure away from said comminuting means and out of the path ofsaid rake at a time when said rake approaches the lower end portion ofits path of reciprocation, the lower end of said pivotally supportedplate being shaped as an are about its pivot point, and the lower end ofsaid screen being shaped as an are about said pivot point, whereby saidgap remains closed in all positions of said pivotally supported plate.

Hauer Apr. 14, 1953 Wormser Feb. 19, 1957 UNITED STATES PATENT OFFICECERHFICATE 0i CGRRECTION Patent No.n 2,885,079 May 5, 1959 ArthurWormser It is hereby certified that error appears in the-printedspecification of the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column '7, line '7, for "rate" read rake line 15, for "on" read one 5column 8, lines 35 and 36, for "estending" read extending Signed andsealed this 29th day of December 1959 (SEAL) Attest:

ROBERT C. WATSON Commissioner of Patents KARL H, AXLINE Attesting()fficer

